Applications, where objects are monitored with respect to their movement are numerous, as for example in sports games. Sports games, such as for example soccer, football, handball, ice hockey, hockey or the like employ rules where one participating party scores when a movable object, such as a ball or the like, crosses a predetermined detection plane, as for example the goal plane defined by goal line and/or a goal frame, e.g. a soccer goal. The question whether the ball completely passed the goal plane is of utmost importance to conclude whether a score has been achieved or not. Traditionally, that decision has been taken by a referee from a visual observation. Especially in scenarios where the ball moves into the direction of the goal and is returned quickly by the goal keeper or a goalpost, it is difficult to determine, whether the ball entered completely into the goal, i.e., whether the ball has sufficiently crossed the goal plane/line.
Apart from camera-based optical systems, some other approaches propose to detect the transition of the ball through a detection plane using electromagnetic fields and/or evaluation signals derived therefrom. Some proposed systems provide magnetic fields of different direction on opposite sides of the detection plane and/or different frequencies and/or different modulations together with sensors within the moving object or the ball under observation. That is to say, a sensor within the movable object may monitor the (electro-) magnetic field and determines that it passed through the detection plane when the orientation of the magnetic field has changed. In that event, the moving object or a transceiver contained therein may transmit information that the movable or moving object has detected transition through the detection plane to a receiver circuit such as to be able to indicate whether the ball was inside the goal or not.
Other systems utilize two antenna loops on each side of the detection plane, wherein each antenna loop receives a high-frequency signal with opposite phase such as to provide magnetic fields cancelling each other out in the detection plane in the middle between the two loops. A third receive antenna loop defining a detection plane is deployed in order to receive a field disturbance of a moving object passing through the set-up such as to be able to conclude, on occurrence of a signal on the receive antenna loop, that a ball or a moving object passed the plane of the receive antenna loop.
In order to provide or to receive the (electro-) magnetic field used for the detection, those systems utilize antenna loops fully encircling an area of interest or detection area within the detection plane, such as for example a goal frame. Those systems suffer from a decreased spatial resolution, as the generation of a precise field configuration over large areas is hardly feasible.
Hence, there is a desire to provide improved systems and methods for determining the transit of a moving or movable object through a detection plane.